1. Field of the Invention
The present invention relates to a balance with a weighing system which is protected against overloading. The weighing system includes a load receiving means and a weighing dish placed on the load receiving means. Two pivotable tilting levers supporting the weighing dish are mounted between the load receiving means and the weighing dish. The tilting levers have outer and inner lever ends, wherein the outer lever ends contact the weighing dish from below and the inner lever ends engage into a vertically displaceable abutment. The abutment is biased by the restoring force of a pre-tensioned spring in such a way that, when an overload is applied, the two tilting levers are pivoted and overcome the force of the spring and form a parallel guide means for the weighing dish which is being lowered.
2. Description of the Related Art
A balance of the above-described type is known from DE-C2-3242156. This reference discloses an overload protection device for a top-loading balance which includes a platform placed on the load receiving means. Two V-shaped and plate-shaped tilting levers rest on the platform. The inner ends of the tilting levers engage under a spring bearing which is arranged axially relative to the load bearing means and is displaceable on the restoring force of a pre-tensioned spring. The weighing dish or a weighing dish support member rests on the outer ends of the tilting levers.
When an overload is applied to the weighing dish, the two tilting levers pivot about the linear support area on the platform and transmit the force acting on the weighing dish into the spring in the abutment or bearing.
This known overload protection device, which is arranged above the measuring cell and outside of the housing, sufficiently protects balances with small nominal loads against damage due to moderate overloading.
In balances having a load range of ten or more kilograms, which additionally for reasons of easy loading must have a structural height which is as low as possible, the above-described overload protection device cannot be utilized in an advantageous manner. On the one hand, the tilting levers which serve as transmission elements and are of sheet metal generally can only transmit small forces or small overloads. On the other hand, the device must be arranged above the weighing cell and, consequently, results in an undesirable increase of the structural height of the balance.